It is now widely accepted that RPVs have the potential to fill several significant military roles. The majority of the effort to date has addressed land based RPV systems and very little has been done on the development of ship based systems.
Use of RPVs in the Naval environment [Shipboard Launch and Recovery system (SLAR) of the RPV] adds a number of new challenges. For the proposed short range RPV in particular, operating from frigate sized and smaller ships means taking off from, and landing on, an unstable moving deck, with severe airwake turbulence from the superstructure and very tight space constraints both during operation and stowage. A strong trend is already emerging in favour of RPVs with a VTOL capability for the maritime role because of the demonstrated difficulties of landing a fixed wing air vehicle on even relatively large and stable ships' decks. On land, the VTOL RPV requires little or no launch and recovery support and hence this area of development has been largely ignored. In the shipboard application this is not true.
Requirements for launch, recovery and handling systems are only just starting to be formulated. However, a consensus is emerging that RPVs should be capable of operating off frigate sized ships in at least sea state 3 with 10.degree. roll, 3.degree. pitch (typically) and ideally up to sea state 5 with 30.degree. roll, 10.degree. pitch compatible with current U.S. and Canadian Navy helicopter operational limits.
Initial RPV placements will probably be on ships which are already operating with one or more helicopters; however, the system must also be adaptable to smaller, non-flight deck equipment ships. On existing flight decks, the goal must be to complement the helicopter capability rather than to displace it. To this extent, the RPV must operate on a non-interference basis and share the already cramped quarters in the hangar. The RPV system must require minimal additional crew members for operation or maintenance, as well as minimizing any additional skill levels.
There are five (5) distinct phases in the launch, recovery and handling of RPVs from small ships; recovery assistance, securing, traversing or deck handling, stowage and of course launch.
Recovery assistance requirements will, to a great extent, depend on the stability characteristics of a number of elements--the UMA, the operating envelope limits and the ship motion and associated airwake turbulence.
A very stable and controllable air vehicle operating in relatively calm conditions may not require any specific recovery assistance other than that provided by the normal RPV operator.
In higher sea states and/or with a less stable air vehicle the operator workload will increase dramatically to the point where some form of recovery assistance becomes mandatory. The Naval helicopter pilot has difficulties under such conditions. The situation is even worse for an RPV operator for several reasons. Although the operator can maintain good visual contact with the RPV, he lacks the "seat of the pants" acceleration feedback. He also has difficulty in judging RPV position since he is, most likely, looking up at the RPV and has no references in the background to provide visual cues as to the RPV's position relative to the ship. Finally, the RPV being a much smaller craft, is far more susceptible to wind shears and high frequency turbulence in the airwake behind the ship's hangar or other superstructure.
Whatever form of recovery assistance is provided, the goal must be to eliminate flight deck personnel during launch and recovery operations.
It is therefore an object of this invention to provide an apparatus suitable for use on shipboard for the recovery of RPVs.
Once landed, the RPV needs to be secured as quickly as possible; ideally before the end of the quiescent period to avoid it sliding across the deck (or worse still, toppling) during the next roll or pitch cycle.
In benign conditions, this may be able to be achieved manually. At higher sea states, an automatic or remotely operated securing device becomes even more essential. Furthermore, a securing system design is also complicated by the diversity of undercarriage configurations proposed for RPVs; for instance four legs, a continuous ring, or skids, and possibly even wheels.
It is therefore an object of this invention to provide such apparatus which permits rapid securement of the RPV to the apparatus minimizing the number of personnel involved. Once on the deck, the RPV must be moved either out of the way to allow helicopter operations, or to a suitable point for refueling, changing payload, dismantling or maintenance, or to a long term stowage area in the hangar or elsewhere.
Although must smaller than a helicopter, the typical RPV still weighs several hundred pounds (one RPV being in the order of about 350 lbs., about 5' tall, 24" around the body and having a rotor diameter of 9') and is not man portable without considerable disassembly. Since disassembly on the flight deck can only be considered in the most benign conditions without putting the vehicle and deck personnel at risk, a handling device is necessary to maintain the security of the RPV. Furthermore, the entire handling phase of both launch and recovery operations must take place quickly and efficiently in order to restore the flight deck to a "ready" status for helicopter operations.
It is therefore an object of the invention to provide some such apparatus which integrates the securing and traversing/handling of the RPV so that the same device performs both functions. This would decrease mission time to launch and traverse since the vehicle would be married to one device for both functions, no time would be lost in changing devices for the next activity. In addition, loss of security during transfer from one device to another would be totally avoided.
In its simplest form, according to one aspect of the invention, a landing and securing platform can be provided for the landing of an RPV thereon and can be released from the landing point to become a dolly which may be maneuvered manually to and from a hangar. Alternatively, the platform can be secured by cables and winched across the flight deck. Ideally to preserve maximum security, the platform is guided along and restrained by some form of track or rail. This track could be either an existing track or a separate lightweight surface mounted track. Any track installation of course must not interfere with helicopter operations or be subject to damage during vertical replenishment. If an existing track is used, the platform should have a means of disengagement from the track inside the hangar, and preferably an auxiliary track to take it to its stowage area.
Ideally, RPV stowage must provide shelter from the environments in both a "ready use" area and a long term storage and maintenance area. In the case of helicopter equipped ships, neither of these areas must interfere with helicopter operations. This represents a significant challenge in an already limited space, especially since it is expected that three or more RPVs will be carried, each of which may have different payload packages and each of which will presumably require a capability for random selection.
The integrated landing/securing/traversing platform can also be used for ready use stowage and to move the RPV into the hangar where it can be broken down for long term stowage. Suitable lifting gear may be provided inside the hangar to allow transfer of complete RPVs or major subassemblies to and from stowage racks.
The launch sequence is essentially the reverse of the landing securing and traversing sequence. The launch/recovery platform preferably provides an umbilical connection to the RPV for the above start up sequences together with a quick release arrangement for both the umbilical connection and the RPV securing device. The launch is almost as critical as the landing phase since the RPV must be released cleanly and lift off during a quiescent period. It is thus a further object of this invention to provide apparatus which permits RPVs to be landed efficiently and safely and methods of its use permitting such safe and efficient landing.
Further and other objects of the invention will be realized by those skilled in the art from the following summary of invention and detailed description of the embodiments thereof.